A gimbal system may incorporate an orientation-dependent device such as an optical detector. The gimbal system has at least two gimbals that offer the optical detector two degrees of rotational freedom via rotary joints. With this rotational freedom, the optical detector may be panned and tilted in order to survey a wide field of view or aim at a specific target.
The gimbal system may be exposed to changing and sometimes harsh environmental conditions. For example, the gimbal system may be used in a marine environment in which saltwater is driven against the housing of the gimbal system, and particularly a rotary joint thereof, through wave action in heavy seas. To ensure robust system performance, sensitive components inside the housing should be isolated from potentially damaging aspects of the ambient environment by sealing any vulnerable rotary joint with a rotary seal. The rotary seal may, for example, be a face seal or a radial seal, each formed with a gasket that creates a movable, fluid-tight barrier between housing surfaces. The housing surfaces may be offset at least generally axially (the face seal), or at least generally radially (the radial seal), from one another.
Both types of rotary seal can be suboptimal for a gimbal system. Each type of rotary seal typically requires high friction to achieve an effective barrier to fluid. However, high friction impedes rotation at the rotary seal and thus requires more power for normal operation, which may necessitate use of a larger motor/drivetrain. A radial seal is subject to coefficient of expansion (COE) mismatch with the housing, which causes a large variation in friction and seal capability with temperature. A face seal can be very sensitive to gap height tolerance stack up between the housing surfaces. All of these drawbacks encourage design of gaskets having a smaller diameter and thus sealing a smaller volume. An improved gasket to create a rotary seal for a gimbal system is needed.